Positioning the light source in a cavity formed in the internal structure is known, the cavity having towards the passenger compartment of the vehicle an aperture covered by the translucent area of the covering. When the light source is active, the light emitted by this source passes through the translucent area, which gives the possibility of creating a bright decor on the interior structure, visible from the passenger compartment of the vehicle.
Such a layout of the light source cannot be achieved when the internal structure is provided for absorbing an impact, for example a head impact of the passenger according to the regulations ECE 21. Indeed, the area including the cavity in which the light source is placed, does not have sufficient resistance to depression for absorbing the energy of the impact.